The present invention relates to a valve for sterile sampling of a liquid sample from a container, comprising a valve body with a valve chamber, a sample inlet in the valve chamber surrounded by a first valve seat, a first valve plug for closing the sample inlet through abutment against the first valve seat, an outlet from the valve chamber, a cleaning inlet in the valve chamber for disinfection fluid, a second valve seat and a second valve plug.
Valves of this type are among others used within the food industry for sampling samples of milk, juice, beer and the like, where there is a need for a sterile sealing valve for sampling of the samples. Such a sterile sealing is also advantageously used within for instance the pharmaceutical industry.
WO 90/12972 discloses a sampling valve with only a single valve seat. The valve seat is arranged around an axially disposed sample inlet, which is closed by displacement of a valve spindle, such that a valve spindle of rubber or a similar ductile material abuts against the valve seat. Moreover, the valve comprises an outlet, which in the mounted condition of the valve extends into the bore from below, and a cleaning inlet extending into the bore from above. As a consequence of this, the valve is adapted to be mounted in such a way in a container that its axis is substantially horizontal, for which reason the mounting of the valve can only take place with a very small degree of freedom. The cleaning inlet is connected with a source of sterilisation fluid through a sterilisation fluid valve.
In respect of this known valve sampling of a liquid sample typically involves the following steps:                1. Prior to cleaning/sterilisation and sampling the valve is in its closed condition, in which only the outlet and the cleaning inlet communicate with one another.        2. A sterilisation fluid is injected in the form of for instance vapour through the cleaning inlet.        3. The sterilisation fluid cleans the surfaces of the axial bore and the outlet, which have been in contact with a previously sampled liquid sample, if any, following which the sterilisation fluid leaves the valve body through the outlet.        4. The sample inlet is opened, whereby there is free communication between the sample inlet, the outlet and the cleaning inlet, and the contents of the container will, if the valve is correctly mounted, flow out of the outlet, following which it can be drawn in the form of a liquid sample.        5. The valve is closed again, following which it is ready for the next sterilisation and sampling.        
At such a sampling it is quite common that an amount of container liquid flows into and at worst through the cleaning inlet. It is therefore necessary to arrange the sterilisation fluid valve for the source of the sterilisation fluid at a safe distance from the cleaning inlet in order not to contaminate the sterilisation fluid valve seat. This makes the sampling difficult, just as an undesirable cylinder clearance is created in the valve system, which in some cases is highly undesirable, as it results in considerable spillage.
DK 174591 discloses a sampling valve with a double valve seat and valve plug corresponding to the valve mentioned in the introduction. In this publication a first valve plug establishes by displacement of a first, interior valve spindle an interior, annular sealing surface against a first valve seat, whereas a second valve plug by displacement of a second, exterior valve spindle establishes an exterior, annular sealing surface against a second valve seat radially relative to the first annular sealing surface. Thus, two valve seats have been established radially relative to an axially disposed sample inlet. The purpose of establishing an additional valve seat is thus to improve the cleaning of the area, which in the closed condition of the valve is pinned between the sealing and the valve seat. This is done by a method substantially similar to the one disclosed in the above international application, but by alternating abutment of the two sealing membranes against the valve seats followed by a cleaning of the valve chamber. The valve according to this publication does not solve the aforementioned problems in respect of leakage of container liquid to the cleaning inlet.